Dual asynchronous mapping of client signals of arbitrary rate

Abstract

A network may include an ingress node that is configured to receive a client signal having a client rate that is one of a multiple different client rates, asynchronously map the client signal into a first frame of a first rate, asynchronously map the first frame into a second frame of a second rate, and output the second frame on the network; an intermediate node that is configured to receive the second frame, recover the first frame from the second frame, asynchronously map the first frame into a third frame of a third rate, and output the third frame on the network, where the intermediate node does not recover the client signal from the first frame; and an egress node that is configured to receive the third frame, recover the first frame from the third frame, recover the client signal from the first frame, and output the client signal.

What is claimed is: 
     
       1. A system, comprising:
 an ingress node configured to:
 receive a client signal comprising a client rate that is one of a plurality of client rates, 
 asynchronously map the client signal into a first frame of a first rate, 
 asynchronously map the first frame into a second frame of a second rate, the second frame comprising a first asynchronously mapped frame, and 
 output the second frame; 
 
 an intermediate node configured to:
 receive the second frame, 
 asynchronously map the first frame into a third frame of a third rate, 
 transfer the third frame through at least a portion of the intermediate node, 
 recover the first frame from the third frame, 
 asynchronously map the first frame into a fourth frame of a fourth rate, and 
 output the fourth frame, the fourth frame comprising a second asynchronously mapped frame, the intermediate node not recovering the client signal or the portion of the client signal from the first frame; and 
 
 an egress node configured to:
 receive the fourth frame, 
 recover the first frame from the fourth frame, 
 recover the client signal from the first frame, and 
 output the client signal. 
 
 
     
     
       2. The system of  claim 1 , where the second rate and the fourth rate are a same rate. 
     
     
       3. The system of  claim 1 , where the second frame and the fourth frame have a same frame structure. 
     
     
       4. The system of  claim 1 , where the client rate, the first rate, and the second rate are independent of each other. 
     
     
       5. The system of  claim 1 , where, when asynchronously mapping the client signal into the first frame of the first rate, the ingress node is configured to:
 partition the client signal into portions, and 
 asynchronously map each of the portions of the client signal into one of a plurality of first frames, where the plurality of first frames includes the first frame. 
 
     
     
       6. The system of  claim 5 , where, when recovering the client signal, the egress node is configured to:
 receive the plurality of first frames, 
 concatenate the plurality of first frames, and 
 recover the client signal from the concatenated plurality of first frames. 
 
     
     
       7. The system of  claim 1 , where the first frame includes a combination of fixed stuff and variable stuff locations that compensate for a difference between the client rate of the client signal and the first rate of the first frame, and
 where the fixed stuff location does not store data associated with the client signal and the variable stuff location selectively stores data associated with the client signal. 
 
     
     
       8. The system of  claim 7 , where the fixed stuff location is one of a plurality of fixed stuff locations, and
 where a number the plurality of fixed stuff locations and a distribution of the plurality of fixed stuff locations are chosen based on the client rate. 
 
     
     
       9. The system of  claim 7 , where one or more of a justification control indicator, a negative justification opportunity, or a positive justification opportunity are used for the variable stuff location. 
     
     
       10. The system of  claim 1 , where the second frame includes a variable stuff location that compensates for a difference between the first rate of the first frame and the second rate of the second frame, and
 where the variable stuff location selectively stores data associated with the client signal, where the second frame includes no fixed stuff location. 
 
     
     
       11. The system of  claim 1 , where the intermediate node includes a switch fabric, and
 where the intermediate node is further configured to:
 transfer the third frame through the switch fabric. 
 
 
     
     
       12. The system of  claim 11 , where, when transferring the third frame, the intermediate node is configured to:
 divide the third frame into a plurality of segments, and 
 separately transfer each of the plurality of segments to the switch fabric. 
 
     
     
       13. The system of  claim 11 , where the switch fabric includes a plurality of switches, each of the plurality of switches storing mapping information that maps data received on a particular ingress link during a particular ingress timeslot to a particular egress timeslot on a particular egress link. 
     
     
       14. The system of  claim 1 , where only the ingress node maps the client signal into the first frame, and only the egress node recovers the client signal from the first frame. 
     
     
       15. A method performed in a network including at least a first node, a second node, and a third node, the method comprising:
 receiving, by the first node, a client signal at a client rate; 
 asynchronously encapsulating, by the first node, the client signal in a first frame of a first rate; 
 asynchronously encapsulating, by the first node, the first frame in a second frame of a second rate, the second frame being a first asynchronously mapped frame; 
 outputting, by the first node, the second frame to the second node; 
 receiving, by the second node, the second frame; 
 extracting, by the second node, the first frame from the second frame; 
 asynchronously encapsulating, by the second node, the first frame in a third frame of a third rate; 
 transferring, by the second node, the third frame through at least a portion of the second node; 
 recovering, by the second node, the first frame from the third frame; 
 asynchronously encapsulating, by the second node, the first frame in a fourth frame of a fourth rate; 
 outputting, by the second node, the fourth frame to the third node, the fourth frame being a second asynchronously mapped frame; 
 receiving, by the third node, the fourth frame; 
 extracting, by the third node, the first frame from the fourth frame; 
 extracting, by the third node, the client signal from the first frame; and 
 outputting, by the third node, the client signal, 
 the client rate, the first rate, the second rate being independent of each other. 
 
     
     
       16. The method of  claim 15 , where the second rate and the fourth rate are a same rate. 
     
     
       17. The method of  claim 15 , where the second frame and the fourth frame comprise a same frame structure. 
     
     
       18. The method of  claim 15 , where asynchronously encapsulating the client signal in the first frame includes asynchronously inverse multiplexing the client signal over a plurality of first frames, and
 where the first frame is one of the plurality of first frames. 
 
     
     
       19. The method of  claim 18 , where extracting the client signal includes:
 receiving the plurality of first frames, 
 concatenating the plurality of first frames, and 
 extracting the client signal from the concatenated plurality of first frames. 
 
     
     
       20. The method of  claim 15 , where the first frame includes a combination of fixed stuff and variable stuff locations, and
 where the fixed stuff location does not store data associated with the client signal and the variable stuff location selectively stores data associated with the client signal. 
 
     
     
       21. The method of  claim 15 , where the second frame includes a variable stuff location and no fixed stuff location, and
 where the variable stuff location selectively stores data associated with the client signal. 
 
     
     
       22. The method of  claim 15 , where the second node includes a switch fabric, and
 where the method further comprises:
 transferring the third frame through the switch fabric. 
 
 
     
     
       23. The method of  claim 22 , where transferring the third frame includes:
 dividing the third frame into a plurality of segments, and 
 separately transferring each of the plurality of segments to the switch fabric. 
 
     
     
       24. The method of  claim 22 , where the switch fabric includes a plurality of switches, each of the plurality of switches storing mapping information that maps data received on a particular ingress link during a particular ingress timeslot to a particular egress timeslot on a particular egress link. 
     
     
       25. An intermediate node in a network that includes an ingress node and an egress node, the intermediate node comprising:
 an ingress line module; 
 an egress line module; and 
 a switch fabric connected to the ingress line module and the egress line module; 
 the ingress line module being configured to:
 receive a first frame from the ingress node,
 the first frame encapsulating a second frame, 
 the second frame encapsulating a client signal, 
 the first frame being associated with a first rate, 
 the second frame being associated with a second rate, 
 the client signal being associated with a third rate, and 
 the first frame comprising a first asynchronously mapped frame, 
 
 recover the second frame from the first frame, 
 asynchronously map the second frame to a third frame that is associated with a fourth rate, and 
 transfer the third frame to the switch fabric, 
 
 the switch fabric being to:
 transfer the third frame to the egress line module, 
 
 the egress line module being configured to:
 recover the second frame from the third frame, 
 asynchronously map the second frame to a fourth frame that is associated with a fifth rate, and 
 output the fourth frame to the egress node, the fourth frame being a second asynchronously mapped frame,
 the intermediate node not recovering the client signal from the second frame. 
 
 
 
     
     
       26. The intermediate node of  claim 25 , where the first rate and the fifth rate are a same rate. 
     
     
       27. The intermediate node of  claim 25 , where the first frame and the fourth frame comprise a same frame structure. 
     
     
       28. The intermediate node of  claim 25 , where, when transferring the third frame to the switch fabric, the ingress line module is configured to:
 divide the third frame into a plurality of segments, and 
 separately transfer each of the plurality of segments to the switch fabric. 
 
     
     
       29. A method for transferring data across a network that includes an ingress node, an egress node, and a plurality of intermediate nodes, the method comprising:
 receiving, at the ingress node, a plurality of client signals that comprise a corresponding plurality of client rates; 
 asynchronously mapping, at the ingress node, each of the plurality of client signals into a plurality of first frames,
 each of the plurality of first frames comprising a same structure and a same rate; 
 
 transporting the plurality of first frames across the network to the egress node via one or more of the plurality of intermediate nodes; 
 asynchronously mapping, within one of the one or more of the plurality of intermediate nodes, one of the plurality of first frames into a second frame; 
 transmitting, within the one of the one or more of the plurality of intermediate nodes, the second frame through at least a portion of the one of the one or more of the plurality of intermediate nodes; 
 recovering, within the one of the one or more of the plurality of intermediate nodes, the one of the plurality of first frames from the second frame; 
 asynchronously mapping, within the one of the one or more of the plurality of intermediate nodes, the one of the plurality of first frames into a third frame; 
 outputting the third frame to the egress node,
 none of the one or more of the intermediate nodes recovering any of the plurality of client signals; and 
 
 recovering the plurality of client signals at the egress node. 
 
     
     
       30. The method of  claim 29 , where one of the ingress node, the intermediate node, or the egress node may function as another one of the egress node, the intermediate node, or the ingress node for another client signal. 
     
     
       31. The method of  claim 29 , where transporting the plurality of first frames across the network includes managing connections in the network based on a collection of the plurality of first frames. 
     
     
       32. The method of  claim 29 , further comprising:
 providing protection for the client signals on a per-first frame level.